Your gut does far more than digest food. As it changes with age, it may influence inflammation, immunity, metabolism, memory, and how well your body holds up over time.

Evidence about the aging gut shows that getting older affects your gut health and overall well-being. Find out how to keep your gut in good working order over time.

A Gut Is Born

Almost immediately after a baby arrives in the world, microbes – mostly beneficial bacteria – begin to populate the colon. Over the next few years, the gut continues to evolve as more microbes move in and establish a community that’s essential to your survival. Though no two gut microbiomes are the same, people have many microbes in common, including bacteroides and other large families of bacteria that account for about 90% of the gut microbe population.

By about age 3, the gut is considered stable and stays that way until midlife, when it begins to evolve again. A “stable” gut doesn’t mean it’s not capable of change, however. Beneficial bacteria coexist with bad bacteria that can make you sick, and the levels of both types of microbes can fluctuate for several reasons. Diet, infection, medication use, and other factors can alter your gut microbe community in a positive or negative way.

Getting older also affects gut function. As you age, your cells don’t reproduce as quickly or as reliably as they did when you were younger, and that can slow down digestion, causing constipation and bloating.

Aging Affects Gut Diversity

Your gut diversity also declines beginning in midlife. Gut diversity refers to the number of different species, or types, of microbes in the gut. Many types of bacteria have specific jobs, such as aiding in digestion, supporting the absorption of minerals in the gut, producing vitamin B vitamins and vitamin K, and protecting the lining of the large intestine itself. Microbial diversity increases the potential for the gut to perform its duties to keep you healthy.

An imbalance in the gut is called dysbiosis, and it’s more common with age. Dysbiosis can result from lower levels of beneficial bacteria and higher levels of bad bacteria. It’s linked to several age-related disorders, such as a weakened immune system that promotes inflammation, and contributes to the risk of cardiovascular disease, cognitive decline, and metabolic disease, such as type 2 diabetes. Dysbiosis can also weaken the gut lining and allow gut bacteria and other compounds to escape into the bloodstream, where they trigger problems.

Everyone ages at different rates. Recent research suggests that greater gut diversity may slow the aging process. In the study, older people with greater gut diversity and higher levels of bacteroides took fewer medications and were half as likely to die 4 years after the study ended. They also had lower levels of LDLcholesterol (the bad type) and higher levels of vitamin D and byproducts of beneficial gut microbes in their blood.

Menopause and Gut Function

Menopause, which nearly always occurs at midlife, alters gut function, too. Menopause is marked by a loss of estrogen, resulting in several symptoms, including hot flashes. The estrobolome is a collection of bacteria in the gut that metabolizes estrogen and plays a role in how much estrogen gets back into the bloodstream, where it may help limit symptoms. Research on the menopausal gut is far from conclusive, but we do know that estrogen loss is linked to loss of gut bacteria diversity, lowering the potential for the estrobolome to “recycle” estrogen. In addition, declining estrogen and progesterone levels could increase gut permeability, worsening inflammation or increasing the risk of infection.

How to Keep Your Gut Young(er)

Eat a plant-based diet with adequate fiber. A balanced eating plan includes the nutrients you need to stay healthy as well as adequate fiber. Fiber feeds beneficial bacteria in the gut that promote diversity, protect the gut lining, and reduce the risk of constipation.

Fiber is found only in plant foods, including whole grains, legumes, lentils, fruit, and vegetables. Most healthy adults need at least 28 grams of fiber daily, but only 3% of people living in the U.S. get that amount. It may be difficult to include enough fiber with a smaller appetite. Choose the highest-fiber foods, such as raspberries, potatoes, lentils, and beans, for the most fiber in the least amount of food.

Follow up with fluid. Fluid works with fiber to help ward off constipation. Water is the best fluid source, but fruits and vegetables are also packed with water, and milk, coffee, juice, and tea count toward fluid requirements, too.

Include probiotic foods. Foods with live active cultures, often called probiotic foods, include yogurt, kefir, kimchi, and sauerkraut found in the refrigerated section. Probiotic foods provide beneficial bacteria. Include at least one serving daily for best results.

Stay active. Regular physical activity helps prevent constipation by increasing blood flow to the gut and helping food pass through faster.

Don’t smoke. Smoking can harm the gut in several ways. Smokers have more heartburn, ulcers, Crohn's disease, and colon cancer. The chemicals in cigarette smoke can upset the balance of the gut environment.

Mind your medications. Older adults take more medications that can affect gut composition and function. Nonsteroidal anti-inflammatory drugs (NSAIDs), proton pump inhibitors used to manage reflux disease, and laxatives are some drugs that affect gut function and composition. Antibiotics kill bad bacteria that make you sick, but they also target beneficial gut bacteria. Taking more than one drug on a regular basis may have an even greater effect on the gut, although people vary in their response to medications. For example, in irritable bowel syndrome (IBS), NSAIDs or antidepressants can either trigger or alleviate symptoms. There’s no need to stop your medications, but it’s a good idea to periodically review them with your doctor or pharmacist to help protect gut function.